• Asian Pacific Journal of Cancer Prevention
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• 제14권3호
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• pp.1865-1877
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• 2013

Vertical variations of polycyclic aromatic hydrocarbon (PAH) concentrations in $PM_{10}$ were investigated in order to assess the factors controlling their behavior in the urban atmosphere of Bangkok City, Thailand. Air samples were collected every three hours for three days at three different levels at Bai-Yok Suit Hotel (site-1 and site-2) and Bai-Yok Sky Hotel (site-3) in February $18^{th}-21^{st}$, 2008. The B[a]P concentration showed a value 0.54 fold, lower than the United Kingdom Expert Panel on Air Quality Standard (UK-EPAQS; i.e. 250 pg $m^{-3}$) at the top level. In contrast, the B[a]P concentrations exhibited, at the ground and middle level, values 1.50 and 1.43 times higher than the UK-EPAQS standard respectively. PAHs displayed a diurnal variation with maximums at night time because of the traffic rush hour coupled with lower nocturnal mixing layer, and the decreased wind speed, which consequently stabilized nocturnal boundary layer and thus enhanced the PAH contents around midnight. By applying Nielsen's technique, the estimated traffic contributions at Site-3 were higher than those of Site-1: about 10% and 22% for Method 1 and Method 2 respectively. These results reflect the more complicated emission sources of PAHs at ground level in comparison with those of higher altitudes. The average values of incremental individual lifetime cancer risk (ILCR) for all sampling sites fell within the range of $10^{-7}-10^{-6}$, being close to the acceptable risk level ($10^{-6}$) but much lower than the priority risk level ($10^{-4}$).

• Computers and Concrete
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• 제19권5호
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• pp.489-499
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• 2017

Self-Compacting Concrete (SCC) is a new technology capable to flow without segregation or any addition of energy which leads to efficient construction and cost savings. In this study, the effect of replacing the Ordinary Portland Cement (OPC) with Fly Ash (FA) on the strength, durability of the concrete was investigated experimentally, and carbon footprint and cost were also assessed. Four different replacement FA ratios (0%, 20%, 40% and 60%) were used to create four SCC mixes. Standard test methods were used to determine the workability, strength, and durability of the SCC mixes including resist chloride ion penetration, water permeability, water absorption, and initial surface absorption. The axial cube compressive strength tests were performed on the SCC mixes at 1, 7, 14, 28 and 35 days. Replacing the OPC with FA had a significant positive impact on chloride iron penetration resistance and water absorption but had a considerable negative impact on the compressive strength. The SCC mix with 60% FA had 36.7% and 15.8% enhancement in the resistance to chloride ion penetration and water absorption, respectively. Evaluation of the carbon footprint and the cost of each SCC mixes showed the $CO_2$ emissions mixes 1, 2, 3 and 4 were significantly reduced by increasing the FA content from 0% to 60%. Compared with the control mix, the cost of all mixes increased when the FA content increased, but no significant differences were seen between the estimated costs of all four mixes.

• 한국태양에너지학회 논문집
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• 제37권4호
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• pp.35-47
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• 2017

Energy efficiency solutions are being pursued as a sustainable approach to reducing energy consumption and related gas emissions across various sectors of the economy. Vacuum Insulation Panel (VIP) is an energy efficient advanced insulation system that facilitates slim but high-performance insulation, based on a porous core material evacuated and encapsulated in a barrier envelope. Although VIP has been applied in buildings for over a decade, it wasn't until recently that efforts have been initiated to propose and adopt a global standard on characterization and testing of VIP. One of the issues regarding VIP is its durability and aging due to pressure and moisture dependent increase of the initial low thermal conductivity with time; more so in building applications. In this paper, the aging of commercially available VIP was investigated experimentally; thermal conductivity was tested in accordance with ISO 8302 standard (guarded hot box method) and long-term durability was estimated based on a non-linear pressure-humidity dependent equation based on study of IEA/ECBCS Annex 39, with the aim of assessing durability of VIP for use in buildings. The center-of-panel thermal conductivity after 25 years based on initial 90% fractile with a confidence level of 90 % for the thermal conductivity (${\lambda}90/90$) ranged from 0.00726-0.00814 (W/m K) for silica core VIP. Significant differences between manufacturer-provided data and measurements of thermal conductivity and internal pressure were observed.

• 대한기계학회논문집B
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• 제38권10호
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• pp.837-844
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• 2014

최근 자동차 제조사는 강화되는 배출가스 규제를 만족시키고 엔진 효율을 향상시키기 위해 다양한 기술을 연구하고 있다. 그 중 직접분사식 초희박 연소기술은 정밀한 연소제어를 통해 연소효율을 극대화 하고 연비를 향상시킬 수 있는 차세대 기술로 평가받고 있다. 기존 가스엔진에 초희박 직접분사기술을 적용하기 위해 기존의 MPI 엔진의 헤드를 재설계하였다. 기존 압축비10:1에서 12:1로 증가시킴으로써 이에 따른 압력선도, 열방출률, 연료소비율 등의 연소특성과 배출가스특성을 파악하였다. 압축비를 증가시킴에 따라 불안정한 연소상태로 인하여 연료소비율의 개선이 어려웠으나 탄화수소(THC)와 질소산화물(NOx)의 배출은 감소되었다.

• 한국대기환경학회지
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• 제28권2호
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• pp.172-181
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• 2012

Mercury is one of the most hazardous air pollutants. Recently, mercury has been a concern in domestic and overseas because it has lethal toxicity, long distance transport, persistence and bioaccumulation in the environment. Stationary combustion sources such as coal-fired power plants, waste incinerators, and cement kilns are the major sources of mercury emissions. The objectives of this study were to measure the concentration for mercury from coal-fired power plants and to calculate emission factor to estimate its emission. The results showed that the mercury concentrations in the flue gas were 1.63-3.03 mg/$Sm^3$ in anthracite-fired power plants (average 2.32 mg/$Sm^3$) and 1.95-3.33 mg/$Sm^3$ in bituminous-fired power plants (average 2.6 mg/$Sm^3$). Mercury emission factor was estimated as 25.74 mg/ton for anthracite-fired power plants and 12.48 mg/ton for bituminous-fired power plants. Because actual measurements are limited in quantity, it is desirable to refine our estimates by extending the actual measurements.

• 환경영향평가
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• 제30권3호
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• pp.155-163
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• 2021

환경영향평가의 훼손수목량은 온실가스 배출량, 임목폐기물 산정 등 다양한 부분에 활용되는 환경지표이다. 지금까지 훼손수목량은 식생조사표의 임목밀도에 의존하였고, 이에 따른 표본편향으로 훼손수목량 추정의 불확실성이 가중되었다. 훼손수목량 추정의 정확성을 높이려면 전수조사를 대안으로 제시할 수 있으나 불가능한 것이 현실이다. 대안으로 드론영상을 이용한 개별 수목 탐지 방법이 있으며, 이 연구는 개별 수목 탐지 방법론으로 표본조사(방형구법)와 드론영상 분석법으로 추정된 훼손수목량을 전수조사 결과와 비교하였다. 연구 결과 전수조사 기준으로 드론 영상 분석법은 25주 과대추정 하였고 방형구법(평균)은 58주 과대 추정하였다. 그러나 기존 환경영향평가에서 시행하는 방형구법은 방형구의 개수, 방형구의 위치에 따른 표본편향의 영향을 많이 받을 것으로 예상된다.

• 한국환경과학회지
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• 제22권1호
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• pp.91-98
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• 2013

In order to study the seasonal patterns and possible origins of air concentrations of volatile organic compounds(VOC), measurements were taken with GC-MS at 3 sampling sites in Jinju for 12 months from Mar. 2010 to Feb. 2011. Atmospheric VOC are sampled on tubes containing solid adsorbents(Tenax TA) with a time resolution of 2hrs. Composition and concentration of VOC are analysed with a GC system equipped with thermal desorption apparatus(ATD). The most abundant compound appeared to be Toluene, Ethylbenzene and m,p-Xylene. The mean concentrations of Benzene were 0.20 ppb at GN site, 0.18 ppb at DA site, and 0.25 ppb at SP site, respectively. VOC concentration showed a strong seasonal variation, with higher concentrations during the spring and lower concentrations during the summer. The results showed that monthly fluctuations in measured VOC concentrations depended on variations in the strength of sources, as well as on photochemical activity and meteorological conditions. In Jinju, the total VOC emissions for 2009 were estimated to be 4,407 ton/year by Clean Air Policy Support System(CAPSS). It is shown that solvent use 57.5%(2,534 ton/yr), waste treatment and disposal 23.3%(1,025 ton/yr), and mobil source-road traffic 12.2%(537 ton/yr) are the most significant anthropogenic source.

• 대기
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• 제19권3호
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• pp.227-235
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• 2009

Global climate warming induced by long-lived greenhouse gases is expected to cause increases in wildfire frequencies and intensity in boreal forest regions of mid- and high-latitudes in the future. Siberian forest fires are one of important sources for air pollutants such as ozone and aerosols over East Asia. Thus an accurate quantification of forest fire influences on air quality is crucial, in particular considering its higher occurrences expected under the future warming climate conditions. We here use the 3-D global chemical transport model (GEOS-Chem) with the satellite constrained fire emissions to quantify Siberian fire effects on ozone concentrations in East Asia. Our focus is mainly on spring 2003 when the largest fires occurred over Siberia in the past decade. We first evaluated the model by comparing to the EANET observations. The model reproduced observed ozone concentrations in spring 2003 with the high $R^2$ of 0.77 but slightly underestimated by 20%. Enhancements in seasonal mean ozone concentrations were estimated from the difference in simulations with and without Siberian fires and amounted up to 24 ppbv over Siberia. Effects of Siberian fires also resulted in 3-10 ppbv incresases in Korea and Japan. These increases account for about 5-15% of the ozone air quality standard of 60 ppbv in Korea, indicating a significant effect of Siberian fires on ozone concentrations. We found however that possible changes in regional meteorology due to Siberian fires may also affect air quality. Further study on the interaction between regional air quality and meteorology is necessary in the future.

• Asian Journal of Atmospheric Environment
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• 제8권1호
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• pp.15-24
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• 2014

The capital city of Himalayan Country Nepal, Kathmandu Valley is surrounded by consecutive high mountains, which limits the air distribution and mixing effects significantly. It in turn generates steady air flow pattern over a year except in monsoon season. The air shed in the Valley is easily trapped by the surrounded mountains and the inversion layer formulated as the cap. The $PM_{10}$ concentration was noticeably higher than the standard level (120 ${\mu}g/m^3$) in urban and suburban area of Kathmandu valley for all seasons except monsoon period. The Valley area experiences similar wind patterns (W, WWS, and S) for a year but the Easterly wind prevails only during the monsoon period. There was low and calm wind blows during the winter season. Because of this air flow structure, the air emission from various sources is accumulated within the valley air, high level of air pollution is frequently recorded with other air polluted cities over the world. In this Valley area, brick kilns are recognized as the major air pollution source followed by vehicles. Mostly Bull Trench Kiln (BKT), Hoffman Kiln and Vertical Shaft Brick Kiln (VSBK) are in operation for brick firing in Kathmandu valley where the fuels such as crushed coal, saw dust, and natural gas are used for processing bricks in this study. Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) was used for screening and quantifying the potential impacts of air emission from firing fuels. The total Environmental Performance Score (EPS) was estimated and the EPS of coal was approximately 2.5 times higher than those of natural gas and saw dust. It is concluded that the crushed coal has more negative impact to the environment and human health than other fuel sources. Concerning the human health and environment point of view, alternative environment friendly firing fuel need to be used for brick industry in the kiln and the air pollution control devices also need to be applied for minimizing the air emissions from the kilns.

• 상하수도학회지
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• 제24권3호
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• pp.319-332
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• 2010

In general, wastewater treatment systems consume high-energy consumption depending on operation characteristics of the facilities. Therefore, greenhouse gas(GHG) reduction activities that are application of digestion gas, induction of renewable energy etc. are conducted to reduce energy consumption and to increase energy independence ratio. In this study, GHG reduction in wastewater treatment system identified, searched application of Clean Development mechanism(CDM) approved methodology. If the methodologies apply to GHG reduction activities such as application of digestion gas, heat pump system using the wastewater as heat source, hydropower using the methodology determined CDM applicability, otherwise through several assumptions calculated expectable GHG reduction emissions and determined CDM applicability. As a result, the order of calculated GHG reduction emission showed that collected and energy generation of digestion gas is 66,775 $tCO_2$/yr, gas engine cogeneration system is 8,182 $tCO_2$/yr, heat pump system using the wastewater as a heat source is 72,715 $tCO_2$/yr, and hydropower is 561 $tCO_2$/yr. Consequently, the order of calculated Certified Emission Reductions(CERs) benefit showed that heat pump system using the wastewater, as a heat source is 1,381 million won/yr was estimated as the highest, followed by a collected and energy generation of digestion gas is 1,268 million won/yr.